Calcium phosphate bions cause increased release of interleukin-6 and interleukin-8 in primary arterial endothelial cells regardless of their shape

Abstract

Background. Calcium phosphate bions are formed under blood supersaturation with calcium and phosphate. Circulating bions provoke endothelial injury via lysosome-dependent cell death accompanied by release of proinflammatory cytokines into the microenvironment.
Aim. To evaluate the cytokine secretion profile of human primary arterial endothelial cells (ECs) exposed to either spherical (CPB-S) or needle-shaped (CPB-N) calcium phosphate bions.
Materials and Methods. CPB-S and CPB-N were added at equal concentrations (100 μL, optical density 0.08-0.10, at 650 nm wavelength) to confluent cultures of primary coronary artery (HCAEC) and internal thoracic artery (HITAEC) endothelial cells in 6-well plates. At 24 h of culture, the cell culture supernatant was collected, and respective cytokines (IL-1β, IL-6, IL-8, IL-10, IL-12, IL-23, tumor necrosis factor-α, and γ-interferon) were measured by an enzyme-linked immunosorbent assay. Expression of cytokine (IL1B, IL6, CXCL8, IL10, IL12A, IL12B, IL23, TNF, IFNG) and cytokine receptor genes (IL1R1, IL1R2, TNFRSF1A, TNFRSF1B) was quantified with the reverse transcription-polymerase chain reaction.
Results. Exposure to both CPB-S and CPB-N led to statistically significant increases in the expression of IL1B, IL6, CXCL8, IL12A, and IL23 genes. HCAEC were characterized by a greater response to CPB at the transcript level compared to HITAEC. Although CPB-N induced a more pronounced cytokine response than CPB-S, such shape-dependent effects were negligible at the protein level. The exposure to CPB-S and CPB-N resulted in elevated release of interleukin-6 by both types of arterial ECs while the interleukin-8 release was augmented exclusively in response to the CPB-N exposure of HITAEC.
Conclusion. Exposure of primary arterial ECs to CPB induced the release of IL-6 and IL-8 due to the expression of respective genes regardless of the CPB shape (spherical or needle-shaped).